非要使用PTFE(聚四氟乙烯)内衬的平底锅时，应保证炉头处于中等或更低温度。另外，绝对不要预热空无一物的平底锅。

If you must use a PTFE-lined pan, keep your stove's burner on medium or lower. Also, never preheat an empty pan.

youdao

非要使用PTFE(聚四氟乙烯)内衬的平底锅时，应保证炉头处于中等或更低温度。另外，绝对不要预热空无一物的平底锅。

If you must use a PTFE-lined pan, keep your stove's burner on media or lower. Also, never preheat an blank pan.

youdao

单级高频脉冲管制冷机直接降低到20 K以下温区存在很大困难，采用多级方案是高频脉冲管制冷机获得更低温度的主要方法。

Use single stage version to reach the temperature of 20 K is a difficulty for high frequency pulse tube cooler (PTC). Multi-stage version is a popular method to reach the low temperature.

youdao